Sorry for being not more specific but I'm not absolutely certain whether
I encountered a bug or did anything wrong:
The (stupid) code below results in a stall forever or not at 'p0.join()'
depending on the value of TROUBLE_MAKER.
Any help, thoughts, comments?
Thank you for your time.
Michael
# ----------------------------------------------------------------------
from multiprocessing import Process, Queue
# bit vector size
BVS=8
#
TROUBLE_MAKER=12 # for greater values p0.join() is never satisfied...
def evaluate(q, id, start=0, stop=2**BVS):
cmin = {0: []}
for mask0 in range(start, stop):
for mask1 in range(0, 2**BVS):
for mask2 in range(mask1, TROUBLE_MAKER):
cmin[0].append((mask0, mask1, mask2))
print 'process %d finished (dict layout: %d/%d)...' % (id,
len(cmin), len(cmin[0]))
q.put(cmin.copy())
q.close()
if __name__ == '__main__':
q0 = Queue()
q1 = Queue()
q2 = Queue()
q3 = Queue()
part = 2**BVS/4
p0 = Process(target=evaluate, args=(q0, 0, 0*part, 1*part),
name='worker_0')
p1 = Process(target=evaluate, args=(q1, 1, 1*part, 2*part),
name='worker_1')
p2 = Process(target=evaluate, args=(q2, 2, 2*part, 3*part),
name='worker_2')
p3 = Process(target=evaluate, args=(q3, 3, 3*part, 4*part),
name='worker_3')
p0.start()
print 'process 0 started...'
p1.start()
print 'process 1 started...'
p2.start()
print 'process 2 started...'
p3.start()
print 'process 3 started...'
# main process stalls at p0.join() for bigger TROUBLE_MAKER
p0.join()
p1.join()
p2.join()
p3.join()
res0 = q0.get()
res1 = q1.get()
res2 = q2.get()
res3 = q3.get()
print 'results fetched...'
# ----------------------------------------------------------------------
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